Roof Ponding Calculator — Calculate Roof Water Ponding Load & Depth

Roof Ponding Calculator

Calculate the weight and load of standing water on flat roofs with our comprehensive calculator. Determine potential structural risks and drainage requirements based on roof area and ponding depth.

Step 1: Roof Specifications

2.0″

Understanding Roof Ponding

Ponding occurs when water accumulates on flat roofs due to inadequate drainage. Just 1 inch of water adds approximately 5.2 lbs per square foot of load, which can exceed structural limits.

Step 2: Calculation Parameters

1.2x

About Water Weight

Water weighs approximately 62.4 pounds per cubic foot. Ponding depth is the critical factor – even small depths over large areas create significant structural loads that may exceed design limits.

Ponding Load Results

Summary
Depth Comparison
Breakdown

Total Water Weight

10,400 lbs
2″ depth over 1,000 sq ft
Roof Area
1,000 sq ft
Ponding Depth
2.0 inches
Water Volume
166.7 ft³
Load per sq ft
10.4 lb/ft²

Depth Comparison Table

Ponding Depth Water Weight Load per sq ft Risk Level

Load Distribution Analysis

Ponding Weight Formula

Weight = Area × (Depth/12) × Water Density × Safety Factor

To calculate ponding weight: Convert depth to feet, multiply by roof area to get volume, multiply by water density, then apply safety factor for structural analysis.

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